A MONOGRAPH OF THE EXISTING CRINOIDS 47 



very obliquely wedge-shaped, about as long as broad, and distally wedge-shaped again 

 and elongate. Except for the few more-or-less oblong brachials at the base of the arms 

 all the brachials have strongly produced and finely serrate distal edges which overlap 

 the bases of those succeeding. This overlapping does not involve the entire distal 

 edges of the segments, but only a comparatively small central portion, so that in a lateral 

 view the appearance is given of overlapping spines. 



Syzygies occur between brachials 3 + 4, again about brachials 16+17, and distally 

 at intervals of usually 4 muscular articulations. 



P! is comparatively slender, though much longer and somewhat stouter than P a , 

 tapering evenly from the base to the tip, 7 mm. long with 16 segments of which the 

 basal 6 are about as long as broad and those following gradually become elongated. 

 P 2 is 4 mm. long, more slender than P,, with 11 segments of which the first 2 are about 

 as long as broad and the remainder are longer than broad. The following pinnules 

 decrease in length to the fifth or sixth, which is 3 mm. long, then gradually increase to 

 9 mm. distally. 



The color in alcohol is brownish yellow, with the cirri somewhat lighter. 



Locality. Albatross station 3963; Laysan Island Light, Hawaiian Islands, bearing 

 N. 5630' E., 6.6 miles distant; 583 meters; bottom temperature 23.2 C.; white sand 

 and broken shells; May 22, 1902 [A. H. Clark, 1908, 1909, 1912, 1918, 1932, 1949; 

 Gisl6n, 1934] (2, U.S.N.M., 22690 [type], 35592). 



History. This species was described under the name of Thalassometra delicata in 

 1908 from two specimens from Albatross station 3963. It was removed to the new 

 genus Cosmiometra in 1909. The two original specimens are still the only ones known. 



COSMIOMETBA DASVBRACHIA H. L. Clark 



Cotmiometra daiybrachia H. L. CLARK, Biol. Res. Fishing Exper. F. I. S. Endeavour, 1909-14, vol. 4, 

 part 1, 1916, p. 24 (detailed description; east of Flinders Island, Bass Strait, 70-100 fathoms), 

 pi. 4, fig. 2. A. H. CLARK, Proc. Biol. Soc. Washington, vol. 31, 1918, p. 42 (listed from 

 Tasmania). 



Diagnostic features. A rather slender species with 20 arms; the cirri, which are 

 arranged in 10 definite columns on a moderate sized rounded conical centrodorsal, are 

 slender and very long, somewhat more than half the length of the arms, with 68-74 

 segments. The arms are about 90 mm. long, and the cirri are 45-50 mm. long. 



Description. The centrodorsal is markedly conical, scarcely 5 mm. in diameter 

 at the base and about 4 mm. high. The cirrus sockets are arranged in 10 columns of 

 3 or 4 each (about 35 altogether), the columns separated in the midradial line by a 

 rather broad area with a finely roughened surface. 



The cirri are about XXXV, 68-74, from 45 to 50 mm. long. The fifth or sixth 

 segment is the longest, much longer than broad, and all the segments but the proximal 

 15 have the distal dorsal edge produced into what looks like a sharp spine when seen 

 from the side. The distal segments, including this dorsal spine, are twice as broad as 

 long. 



The radials are completely concealed except for the small distolateral corner, which 

 is visible in the interradial angles of the calyx. The IBr, are cresccntic with the proxi- 

 mal margin strongly convex and the distal correspondingly concave; excepting only the 

 distal median portion, the whole surface is rough and spinulose, especially the lateral 

 margins. The IBr 2 (axillaries) are rhomboidal with the anterior margins slightly con- 



